1. Field of the Invention
The present invention is generally related to a time-indicating apparatus, and more particularly to an apparatus for indicating the passage of time, composition and forming method thereof.
2. Description of the Prior Art
Generally, food is considered to be safe within the shelf life. However, it is generally not true. For instance, the temperature of the environment for storing food is so high or the time of the food exposing to air is so long to result in bacterial overgrowth or food spoilage and thereby to affect human health. In order to avoid consumers from eating spoiled food, new packaging technology to indicate the state of food has been researched by various companies and academic organizations. For example, a time-temperature indicator (TTI) has a function of indicating the temperature and time variations of a product (such as food) undergoing the processes of storage, transportation, and sale by color change. It can indicate the degree of quality decrease due to the temperature and time variations of a product from the time of completing fabrication until the time of utilization so as to ensure the safety of the product.
At present, such commercialized products comprise VITSAB®, Life Lines®, 3M™, DeltaTrak®, OnVu™ and so forth. Their operation principles comprise enzyme catalysis, diffusion mechanism, solid-state polymerization, etc. These products have disadvantages of inconvenience in usage and high cost. Therefore, developing a novel apparatus for indicating the passage of time is required to fulfill usage convenience, precise indication, and low cost.